SOLVENT-DEPENDENT QUENCHING OF THE LOWEST EXCITED SINGLET-STATE OF 9,10-DICHLOROANTHRACENE BY GROUND-STATE 2,5-DIMETHYLHEXA-2,4-DIENE YIELDING 9-CHLOROANTHRACENE IN ACETONITRILE OR THE [4-HEPTANE(2]ADDUCT IN N)

In acetonitrile, an exciplex formed between the lowest excited singlet state ((1)DCA) of 9,10-dichloroanthracene (DCA) and ground-state 2,5 -dimethylhexa-2,4-diene (DMHD) generates the DCA radical anion as an i ntermediate for dechlorination of DCA yielding 9-chloroanthracene. In n-heptane, however, quenching of 1DCA by DMHD forms no exciplex and a dibenzobicyclo[2.2.2]octadiene-type compound (the [4+2] adduct) is ob tained as the final product.